nimh batteries died?
 

i have two elite 4500 mah 6 cell packs for my brushless boat. the packs sat all winter and when i went to charge them they both seemed to be at 0.00 volts :gasp: ive been cycling them individually on my 989 but they don't seem to be discharging fully as the discharge mah is less than the charge mah...i cycled one of the packs 3 times at .5 amp charge/1.0 amp discharge (took forever) after that was done i discharged at 10 amps and it didn't discharge as much as it had just charged. (put in about 3400 mah, took out about 2400) now im trying charging at 4.5 amps (1C) to see what itl put into the battery. oh and i have the peak mv pumped up to 11 (temp sensor is set to 130 to prevent overcharging)

does anyone have any thoughts as to the lack of fully discharging, or any other ideas to help these batteries

i know i should get lipo but i just bought one for my savage and have no money:oops:

thanks

NiMH are less affected by long term storage than NiCd. But, they will still crystalize if left on the shelf for a long period. So long as they weren't ever overcharged, you can usually revive them quite a bit since they don't hold a memory like NiCd do.

If you want to really compare input/output mAH, you need to charge/discharge at the same rate. Otherwise by discharging at a higher rate the voltage will drop more quickly that it rose while charging and you wont pull as much out before hitting the cut-off.

Though like you said, if you charge it afterwards just see how much goes back in. It works but you can eliminate that step by cycling with the same rate for charge/discharge.

ok, thanks. it finished charging at 1c and only put in 3400 mah, im going to try one cycle at 3 amps both charge and dischage and see what i get. maybe after i actually stick this in the boat ill get a full charge (hopefully)

Yeah maybe. Large currents can actually help revive cells because it breaks up the clusters inside the cell that have accrued over time.

I still run a lot with NiMhs - a yr is a long time to sit, it'll take a while to get them back as far as they're going to recover. You should be encouraged they are doing as well as they are so soon. Implies the Elites are pretty decent cells.

well thats good to hear, thanks, yeah im really hoping once i start actually using them theyll improve more. my brushless boat already drained the two 4500 packs in about 7 minutes, i cant imagine going much lower lol

btw, is it ok to charge them in series as a 14.4 volt pack?

Anytime I've done that, I always felt one batt got a better charge than the other - this is the big reason I have two chargers. Theoretically, yes. But both need to be at almost the same starting voltage and be as alike as possible so they'll present the same resistance to the charging voltage so they'll be charged equally.

Try it and if one batt is hotter than the other, they're not charging equally.

ok, thanks, and since we're on the topic of batteries ill ask this...i have a 4s2p 8000mah lipo, do i enter it into my 989 as as a 4 cell lipo? even though it has 8 cells (i think)

Yes, on both counts. If you told it eight cells, it would charge the batt thinking it was an 8S1P. But - I'm guessing about your charger here - the connected voltage would be wrong and it wouldn't charge it that way and give you some kind of error message - at least my Ice would. Connected voltage from the pac has to be within certain range based on number of cells you input. Otherwise, would be a great way to get in trouble.

ok, thanks, yeah my 989 gives me an error if i input the voltage wrong, id rather get it right the first time though and not "test" the intelligence of it on my lipo:lol: